A bend with a curvature radius of at least 1D – without an additional straight duct section upstream of the volume flow rate measuring unit – has only a negligible effect on the volume flow rate accuracy.

The volume flow rate accuracy ΔV applies to a straight upstream section of the duct. Bends, junctions or a narrowing or widening of the duct cause turbulence that may affect measurement. Duct connections, e.g. branches off the main duct, must comply with EN 1505. Some installation situations require straight duct sections upstream.

Space required for commissioning and maintenance

Sufficient space must be kept clear near any attachments to allow for commissioning and maintenance. It may be necessary to provide sufficiently sized inspection access openings.

Space required

Attachments

①

②

③

Attachments

mm

Without attachments

200

200

200

VARYCONTROL

Universal controller

300

320

300

LABCONTROL

EASYLAB

370

350

400

Space required

Nominal size

①

②

③

Nominal size

mm

125 – 200

100

100

D

250 – 400

100

160

D

D: Casing diameter

Volume flow rate calculation for air density 1.2 kg/m³

Calculation conditions

The volume flow rate is calculated based on the measured effective pressure.

The effective pressure is measured using an electronic manometer or an inclined tube manometer

Air density ρ = 1.2 kg/m³

Given data

VMRK/160

Δpw = 100 Pa (manometer reading of effective pressure)

Volume flow rate V [m³/h]

Unit data

K value from table: K = 54 m³/h (15.1 l/s)

Principal dimensions

ØD [mm]

VAV terminal units made of stainless steel: Outer diameter of the spigot

VAV terminal units made of plastic: Inside diameter of the connecting spigot

ØD₁ [mm]

Pitch circle diameter of flanges

ØD₂ [mm]

Outer diameter of flanges

ØD₄ [mm]

Inside diameter of the screw holes of flanges

L [mm]

Length of unit including connecting spigot

L₁ [mm]

Length of casing or acoustic cladding

B [mm]

Duct width

B₁ [mm]

Screw hole pitch of flange (horizontal)

B₂ [mm]

Outside dimension of flange (width)

B₃ [mm]

Width of device

H [mm]

Duct height

H₁ [mm]

Screw hole pitch of flange (vertical)

H₂ [mm]

Outside dimension of flange (height)

H₃ [mm]

Unit height

n [ ]

Number of flange screw holes

T [mm]

Flange thickness

m [kg]

Weight including attachments for the automatic differential pressure measurement

Nomenclature

Vnom [m³/h] and [l/s]

Nominal volume flow rate (100 %)

Vmin [m³/h] and [l/s]

Volume flow rate

ΔV [± %]

Volume flow rate accuracy

K value [m³/h] and [l/s]

Unit-related constant for air density 1.2 kg/m³

Δpw [Pa]

Effective pressure

Δpst [%]

Static differential pressure in relation to the measured effective pressure

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Your message is send and will be processed shortly.Our department for Service-Requests will contact you asap.For general question regarding products or services you can also call:Tel.: +91 (0) 22 6775-1600 | Fax: +91 (0) 226775-1613